Expression of Ccdc85C, a causative protein for murine hydrocephalus, in the mammary gland tumors of dogs.

Coiled-coil domain containing 85c (Ccdc85c) is a causative gene for hemorrhagic hydrocephalus mouse which shows hydrocephalus with frequent brain hemorrhage and formation of subcortical band heterotopia. A previous study revealed that Ccdc85C protein is expressed in the systemic simple epithelial cells with proliferative activity in rats and suggested that Ccdc85C expression may be related to the cell proliferation of simple epithelial cells. To reveal the roles of Ccdc85C in the proliferative lesion, we examined the expression patterns of Ccdc85C in the mammary gland tumor of dogs, a common representative tumor derived from simple epithelial cells. In canine mammary gland tumors, Ccdc85C was expressed at the apical junctions of the luminal epithelial cells. Ccdc85C was also distributed throughout the entire cytoplasm of the myoepithelial cells. Ccdc85C expression was observed at the epithelial cells with luminal structures, but was not observed at the epithelial cells forming sheet growth pattern without luminal structure. In carcinomas, Ccdc85C expression in mammary tumor tissue tended to be weaker than that in surrounding normal mammary gland tissue. Ccdc85C is known to cause neurological diseases such as hydrocephalus, and subcortical heterotopia, and the present study is the first to demonstrate Ccdc85C expression in canine mammary tumors and a relationship between Ccdc85C expression and tumor malignancy.